JP6652678B1 - Friction transmission belt and method of manufacturing the same - Google Patents

Abstract

To provide a friction transmission belt having high durability when wet, high transmission performance for a long period of time, and high productivity. A friction transmission belt is prepared by forming a friction transmission surface with a fiber member containing cellulosic fibers and a composite fiber layer containing an isocyanate compound and a resin component. The ratio of the isocyanate compound and the resin component in the composite fiber layer may be about 2 to 15% by mass, respectively. The isocyanate compound may be a thermal reaction type isocyanate compound. The thermal reaction type isocyanate compound may have a dissociation temperature of 120 ° C. or higher. The resin component may be a hydrophilic resin. The cellulosic fiber may be a spun yarn formed of cellulose. The fiber member may further include a synthetic fiber. The friction transmission belt may be a V-ribbed belt. [Selection diagram] Fig. 1

Description

  The present invention relates to a friction transmission belt (such as a V-ribbed belt) in which a friction transmission surface is covered with a cloth (such as a knitted fabric), has high transmission efficiency, and has improved quietness (or quietness or sound generation resistance), and a method of manufacturing the same. About.

  2. Description of the Related Art Friction transmission belts are widely used for driving auxiliary equipment of automobiles and driving agricultural machines. Examples of the friction transmission belt include a flat belt, a V-belt, and a V-ribbed belt, and are distinguished from a meshing transmission belt such as a toothed belt that transmits power by mechanically fitting a pulley and a belt tooth portion. Used. In some friction transmission belts, a friction transmission surface is coated with a fiber member in order to increase wear resistance or adjust a friction coefficient. A woven fabric, a knitted fabric, a nonwoven fabric, or the like can be applied to the fiber member, and various fibers can be used as fibers constituting these fiber members in accordance with requirements such as abrasion resistance and water absorption.

  For example, Japanese Patent Application Laid-Open No. 2014-209028 (Patent Document 1) discloses that a knitting ratio of a polyester-based composite yarn which is a bulky processed yarn and a cellulose-based natural spun yarn and the knitting ratio of the cellulose-based natural spun yarn is a polyester-based composite yarn A V-ribbed belt in which a friction transmission surface is covered with a knitted fabric having a knitting ratio equal to or higher than the knitting ratio is disclosed. According to this document, by adjusting the knitting ratio between the polyester-based composite yarn and the cellulose-based natural spun yarn, the friction coefficient of the friction transmission surface in the dry state and the friction coefficient of the friction transmission surface in the wet state are increased. It is described that the reduction can be suppressed together and the difference in friction coefficient between the dry state and the wet state can be sufficiently reduced.

  This V-ribbed belt exhibits a certain effect in suppressing occurrence of abnormal noise due to so-called "stick slip" in which a large slip occurs intermittently between the belt and the pulley. However, this V-ribbed belt requires a cellulose-based natural spun yarn having low abrasion resistance, and as the belt is used, the cellulose-based natural spun yarn falls off the frictional power transmission surface, and the noise tends to be generated. Yes, improvements were required.

  Further, in this V-ribbed belt, an adhesion treatment such as a dipping treatment with rubber glue is described in order to improve the adhesion between the knitted fabric and the compression layer. For such an adhesive treatment, in industrial production, usually, a method is employed in which a fiber member such as the knitted fabric is dipped in an immersion liquid containing an adhesive component and then dried in a hot-air drying oven with a pin tenter. However, the fibrous member impregnated with the adhesive component is liable to have a reduced releasability from the pin of the pin tenter. When the releasability from the pin is reduced, problems such as deformation or breakage of the fiber member and bending or breaking of the pin of the tenter occur.

  As a method for improving the releasability of a cloth from a pin tenter, Japanese Utility Model Application Laid-Open No. 6-22393 (Patent Document 2) discloses a pin tenter in which a fluorine resin layer is provided on the surface of a pin planted in a pin sheet. I have. However, in this method, the equipment needs to be changed, and the economy is low.

JP 2014-209028 A (Claim 1, Paragraph [0011], Example) JP-A-6-22393 (Claim 1)

  Accordingly, an object of the present invention is to provide a friction transmission belt having high durability when wet, high transmission performance for a long period of time, and high productivity, and a method of manufacturing the same.

  Another object of the present invention is to provide a friction transmission belt which has high soundproofing properties and can maintain soundproofing when wet, for a long period of time, and a method of manufacturing the same.

  Still another object of the present invention is to provide a friction transmission belt that can be easily manufactured with a small environmental load, and a method of manufacturing the same.

  Another object of the present invention is to provide a friction transmission belt having excellent wear resistance and a method of manufacturing the same.

  Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and found that a friction transmission surface (power transmission surface) that comes into contact with a pulley is a composite fiber layer containing a cellulose member containing a cellulose-based fiber and an isocyanate compound and a resin component. Thus, the present invention was found to be able to improve the durability when wet, improve the transmission performance over a long period of time, and improve the productivity, and completed the present invention.

  That is, the friction transmission belt of the present invention is a friction transmission belt in which the friction transmission surface is formed of a fiber member, a composite fiber layer containing an isocyanate compound and a resin component, and the fiber member includes cellulosic fibers. The ratio of the isocyanate compound and the resin component in the composite fiber layer may be about 2 to 15% by mass, respectively. The mass ratio between the isocyanate compound and the resin component may be about 95: 5 to 20:80. The isocyanate compound may be a thermal reaction type isocyanate compound (blocked isocyanate compound). The thermal reaction type isocyanate compound may have a dissociation temperature of 120 ° C. or higher. The resin component may be a hydrophilic resin. The cellulosic fiber may be a spun yarn formed of cellulose. The fiber member may further include a synthetic fiber. The friction transmission belt may be a V-ribbed belt.

  In the present invention, a fiber member is immersed in a liquid composition containing an isocyanate compound and a resin component, and then the fiber member impregnated with the liquid composition is heat-set using a pin tenter to form a composite fiber layer sheet. The method also includes a method of manufacturing the friction transmission belt including a composite fiber layer forming step. The liquid composition may be an aqueous solution containing a heat-reactive isocyanate compound and a hydrophilic resin. In the composite fiber layer forming step, the fiber member impregnated with the liquid composition by immersion may be dried at a temperature lower than the dissociation temperature of the heat-reactive isocyanate compound. The ratio of the isocyanate compound and the resin component in the liquid composition may be about 1 to 8% by mass, respectively. The mass ratio between the isocyanate compound and the resin component in the liquid composition may be the former: the latter = 95: 5 to 20:80.

  In the present invention, the friction transmission surface of the friction transmission belt is formed of a fiber member containing cellulosic fibers and a composite fiber layer containing an isocyanate compound and a resin component. In addition, in the manufacturing process of the composite fiber layer, the release property from the pin of the precursor (sheet for composite fiber layer) obtained even after the tenter treatment can be improved in the production process of the composite fiber layer, thereby improving the productivity (workability). Is also expensive. In particular, by combining the isocyanate compound and the resin component at a specific ratio, the soundproofing when wet can be improved, and the soundproofing when wet can be maintained for a long time. When a heat-reactive isocyanate compound is used as the isocyanate compound, the belt does not hinder the elongation of the knitted fabric during molding, and can be hardened after vulcanization of the belt to improve abrasion resistance. The productivity of the power transmission belt can be improved. Further, when the immersion liquid containing the isocyanate compound and the resin component is prepared in an aqueous system, the preparation is simpler and the environmental load is smaller than that of a resorcinol-formalin-latex liquid (RFL liquid) generally used as a fabric treatment agent. . Further, the abrasion resistance is excellent, and the abrasion resistance can be further improved by adjusting the fibers constituting the fiber member.

FIG. 1 is a schematic sectional view showing an example of the friction transmission belt of the present invention. FIG. 2 is a schematic diagram for explaining a composite fiber layer forming step in the method of manufacturing a friction transmission belt of the present invention. FIG. 3 is a schematic diagram showing the pin arrangement in the pin tenter component used in the example. FIG. 4 is a schematic diagram showing a layout of a test machine used in the durability test under the durability test conditions in the example. FIG. 5 is a schematic diagram showing a layout of a test machine used in a wear test under wear test conditions in the example.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings as necessary. The friction transmission belt of the present invention is not particularly limited as long as it has a friction transmission surface that can contact the pulley, and may be a V belt, a V-ribbed belt, a flat belt, or the like. Further, the friction transmission belt may be a belt on which a friction transmission portion (such as a rib) is formed, and a typical transmission belt is formed with a plurality of V-shaped rib portions extending in a belt circumferential direction. It is a highly efficient V-ribbed belt. In the present invention as well, since the effect of improving the durability when wet (particularly, sound resistance) is the greatest, there is also a demand for the improvement in durability (particularly sound resistance) when wet among friction transmission belts. It can be particularly suitably used for a particularly strong V-ribbed belt.

  As shown in FIG. 1, a friction transmission belt (V-ribbed belt) 1 of the present invention forms an extension layer 4 which forms a belt back surface (outer peripheral surface of the belt) and is formed of a cover canvas (woven fabric, knitted fabric, nonwoven fabric, etc.). And a compression layer (compressed rubber layer) 2 provided on the inner peripheral side of the stretched layer, and a surface (inner peripheral surface) of the compressed layer (compressed rubber layer) 2 covered (laminated) to form an inner peripheral surface of the belt. It comprises a composite fiber layer 5 formed and capable of contacting a pulley, and a core 3 buried between the extension layer 4 and the compression layer 2 along the belt longitudinal direction (perimeter direction). In this example, the core 3 is a cord (twisted cord) arranged at a predetermined interval in the belt width direction, and is in contact with the extension layer 4 and the compression layer 2 and is interposed between both layers.

  A plurality of V-shaped grooves extending in the longitudinal direction of the belt are formed in the compression layer 2, and a plurality of ribs having a V-shaped (inverted trapezoidal) cross-section are formed between the grooves. It is covered with a fiber layer 5. The two inclined surfaces of the rib can be brought into contact with the pulley via the composite fiber layer 5, and the composite fiber layer 5 includes a fiber member containing cellulosic fibers, an isocyanate compound and a resin component.

  The present invention is suitably applied to a transmission belt in which a friction transmission surface (or a friction transmission portion) with a pulley is formed on the compression layer 2. The friction transmission belt of the present invention is not limited to the above-described structure. For example, the extension layer 4 may be formed of a rubber composition, and the core 3 and the extension layer 4 are provided between the compression layer 2 and the extension layer 4. Alternatively, an adhesive layer may be interposed in order to improve the adhesiveness with the compression layer 2. The core 3 need only be embedded between the extension layer 4 and the compression layer 2. For example, the core 3 may be embedded in the compression layer 2 or may be embedded in the compression layer 2 while being in contact with the extension layer 4. Further, the core 3 may be embedded in the adhesive layer, or the core 3 may be embedded between the compression layer 2 and the adhesive layer or between the adhesive layer and the extension layer 4.

  Hereinafter, details of each member constituting the belt and a method of manufacturing the belt will be described.

[Composite fiber layer]
The composite fiber layer contains a fiber member, an isocyanate compound and a resin component.

(Fiber members)
In the present invention, since the fibers constituting the fiber member include the cellulosic fibers, they have excellent water absorption on the friction transmission surface, a water film is not easily formed between the pulley and the belt, the occurrence of stick-slip is suppressed, and High durability in water and sound resistance.

(A) Cellulose-based fiber Cellulose-based fibers include cellulose fibers (cellulose fibers derived from plants, animals, bacteria, and the like) and fibers of cellulose derivatives.

  As the cellulose fiber, for example, wood pulp (conifer, hardwood pulp, etc.), bamboo fiber, sugarcane fiber, seed wool fiber (cotton fiber (cotton linter), kapok, etc.), gin skin fiber (hemp, kozo, mitsumata, etc.), Cellulose fibers (pulp fibers) derived from natural plants such as leaf fibers (such as Manila hemp and New Zealand hemp); cellulose fibers derived from animals such as sea squirt; bacterial cellulose fibers; and algal cellulose.

  Examples of the cellulose derivative fibers include cellulose ester fibers; regenerated cellulose fibers (rayon, cupra, lyocell, etc.).

  These cellulosic fibers can be used alone or in combination of two or more. Among them, from the viewpoint of water absorption, cellulose fibers such as cotton fibers and hemp, and regenerated cellulose fibers such as rayon are preferable, and cellulose fibers such as cotton fibers are particularly preferable.

  The cellulosic fiber may be a short fiber, but from the viewpoint of strength, a spun yarn (spun yarn) obtained by twisting a long fiber and a short fiber is preferable. The long fiber may be a monofilament yarn or a multifilament yarn. The multifilament yarn may be untwisted or twisted. The twisted yarn may be a plurality of single twisted yarns as a primary twisted yarn, for example, a twisted yarn, a piece twisted yarn, a Lang twisted yarn, etc., and the single twisted yarn and the original yarn (non-twisted yarn) are aligned and twisted. Warp yarn (for example, wall twisted yarn) may be used. Among them, in the case of the cellulose fiber, a spun yarn or a multifilament yarn is preferable, and a spun yarn is particularly preferable.

  In the case of spun yarn, the thickness (count) of the cellulosic fiber (particularly, cellulose fiber) is, for example, about 5 to 100 count, preferably about 10 to 80 count, more preferably about 20 to 70 count (particularly about 30 to 50 count). It is. If the thickness is too small, the mechanical properties of the composite fiber layer may decrease, and if it is too large, the water absorption may decrease.

(B) Synthetic fiber In addition to the cellulosic fiber, the fiber member is used in addition to the cellulosic fiber in order to suppress the wear of the cellulosic fiber and maintain the durability (particularly, sound resistance) when wet, over a long period of time. Synthetic fibers may be further included.

Examples of the synthetic fibers include polyolefin fibers (polyethylene fibers, polypropylene fibers, etc.), vinyl alcohol fibers (polyvinyl alcohol, ethylene-vinyl alcohol copolymer fibers, vinylon, etc.), and polyamide fibers (polyamide 6 fibers, polyamide 66 fibers). , Aliphatic polyamide fiber such as polyamide 46 fiber, aromatic polyamide fiber such as aramid fiber, etc.), acrylic fiber, polyester fiber [polyethylene terephthalate (PET) fiber, polypropylene terephthalate (PPT) fiber, polytrimethylene terephthalate (PTT) fiber , polybutylene terephthalate (PBT) fibers, _{C 2-4} alkylene _{C 6-14} arylate fibers such as polyethylene naphthalate (PEN) fibers, polyarylate fibers, etc.], Li paraphenylene benzobisoxazole (PBO) fibers, and polyurethane fibers. These synthetic fibers can be used alone or in combination of two or more.

  Synthetic fibers may be short fibers as well as cellulosic fibers, but from the viewpoint of strength, monofilament yarns or multifilament yarns which are long fibers are preferable, and multifilament yarns are particularly preferable. The multifilament yarn may be untwisted or twisted. The twisted yarn may be a plurality of single twisted yarns as a primary twisted yarn, for example, a twisted yarn, a piece twisted yarn, a Lang twisted yarn, etc., and the single twisted yarn and the original yarn (non-twisted yarn) are aligned and twisted. Warp yarn (for example, wall twisted yarn) may be used.

  The multifilament yarn (or twisted yarn) may be a composite yarn (or composite fiber) formed by a plurality of fibers (or yarns). The composite yarn (twist yarn) may be a covering yarn [yarn (twist yarn) including a core yarn and a sheath yarn wound (covered) around this core yarn]. The composite yarn may be a composite yarn of the cellulosic fiber and the synthetic fiber, but a composite fiber of the synthetic fibers (a composite yarn of a synthetic fiber) is generally used.

  The composite yarn of synthetic fibers is, for example, a composite yarn in which a plurality of polyester fibers (for example, PET fibers and PTT fibers) are conjugated, a covering yarn in which both the core yarn and the sheath yarn are composed of synthetic fibers [for example, a core yarn and One of the sheath yarns was formed of a stretchable fiber, for example, a core yarn was formed of a stretchable fiber such as a polyurethane fiber (PU fiber), and a sheath yarn was formed of a polyester fiber (PET fiber or the like). Covering yarn or composite yarn].

  In the present invention, in order to improve the wear resistance of the composite fiber layer, and to suppress the rubber from oozing out on the friction transmission surface (or the surface of the fiber member), a bulky processed yarn having a large cross-sectional bulk, for example, Including a plurality of fibers, a crimped conjugate yarn (a composite yarn of a crimp fiber), a covering yarn obtained by covering a core yarn with the synthetic fiber, a crimped yarn (a yarn of the crimped synthetic fiber), Woolly-processed yarn, taslan-processed yarn, interlaced-processed yarn, and the like are preferable, and conjugate yarn and covering yarn are particularly preferable. The conjugate yarn has a cross-sectional structure in which a plurality of polymers are phase-separated and bonded in the fiber axis direction, and by heat treatment, a crimp is generated by heat treatment, utilizing a difference in thermal shrinkage of the polymer. It is a bulky yarn. The covering yarn is a bulky processed yarn in which the cross-section of the whole yarn is increased by winding (covering) another yarn around the surface of the core yarn. Typical bulky yarns are polyester-based composite yarns, for example, composite yarns conjugated with PTT and PET (PTT / PET conjugate yarns), composite yarns conjugated with PBT and PET (PBT / PET conjugated yarns) A composite yarn (eg, PET / PU covering yarn) obtained by winding a polyester fiber (eg, PET fiber) around the surface of a polyurethane (PU) yarn (PU elastic yarn) as a core yarn and covering the surface; Covering yarns such as a composite yarn (PA / PU covering yarn) obtained by covering a polyamide (PA) with a PU yarn as a core yarn can be exemplified. Among these composite yarns, a PTT / PET conjugate yarn or a PET / PU covering yarn is preferable from the viewpoint of excellent stretchability and abrasion resistance.

  Such a bulky processed yarn makes the fiber member bulky and the fiber has elasticity. Therefore, when the bulky yarn is used, it is possible to prevent the rubber of the belt main body from oozing to the friction transmission surface (or the surface of the fiber member) due to the bulkiness, and to increase the friction coefficient in the dry state and the wet state in the friction transmission surface. Of the friction coefficient can be prevented. In addition, since the friction transmission surface has a high water absorbing ability due to the cellulosic fiber (or spun yarn), a reduction in the friction coefficient of the friction transmission surface in the wet state is prevented, and the friction coefficient between the dry state and the wet state is reduced. The difference can be made sufficiently small.

  The fineness of the synthetic fiber (particularly, multifilament yarn) may be, for example, about 20 to 600 dtex, preferably about 50 to 300 dtex, and more preferably about 60 to 200 dtex (particularly 70 to 100 dtex).

  The ratio of the synthetic fiber may be, for example, 200 parts by mass or less (for example, 0 to 200 parts by mass) with respect to 100 parts by mass of the cellulosic fiber, for example, 1 to 100 parts by mass, preferably 3 to 80 parts by mass ( For example, about 5 to 50 parts by mass), more preferably about 10 to 40 parts by mass (particularly 20 to 30 parts by mass). In applications where abrasion resistance is important, the proportion of the synthetic fibers is, for example, about 10 to 200 parts by mass, preferably about 30 to 100 parts by mass, per 100 parts by mass of the cellulosic fibers. Further, from the viewpoint of excellent balance of durability, sound resistance, abrasion resistance, etc., the proportion of the synthetic fiber is more preferably 50 to 80 parts by mass, and more preferably 60 to 70 parts by mass with respect to 100 parts by mass of the cellulosic fiber. Is most preferred. If the proportion of the synthetic fibers is too large, the water absorption of the composite fiber layer may decrease, and the durability (particularly, sound resistance) when wet may decrease.

(C) Other Fibers The fiber member may further include other fibers in addition to the cellulosic fibers and the synthetic fibers. Other fibers include animal-derived fibers such as wool and silk, and inorganic fibers such as carbon fibers, glass fibers, and metal fibers. The ratio of the other fibers may be 100 parts by mass or less (for example, 0 to 100 parts by mass) with respect to 100 parts by mass of the cellulosic fiber, for example, 0.1 to 30 parts by mass, preferably 0.5 to 20 parts by mass. It is about 1 part by mass, more preferably about 1 to 10 parts by mass. If the proportion of the other fibers is too large, the water absorption of the composite fiber layer may be reduced, and the durability (particularly, sound resistance) when wet may be reduced.

(D) Structure of Fiber Member The fiber member may be in any form (structure) capable of forming the friction transmission surface of the transmission belt, and is usually at least one type of cloth (knitted cloth, woven cloth, nonwoven cloth, or the like). Or canvas). Of these fabrics, it is preferable to form the fiber member with a knitted fabric. Since the knitted fabric has excellent elasticity, it can expand following the flow of rubber during vulcanization, preventing the rubber from being exposed to the friction transmission surface, and providing durability when exposed to water (especially sound resistance). ) Can be improved. Further, it is suitable for laminating the fiber members along the contour (rib shape or the like) of the friction transmission surface.

  The knitted fabric is formed by forming loops without interlacing the yarns in a straight line. That is, a knitted fabric (structure) is formed by knitting a knitted fabric by forming one or more knitting yarns into a stitch (loop), and hooking the next yarn on the loop to continuously form a new loop. Having. Therefore, the elastic member has high elasticity, can be easily laminated along the uneven surface such as the rib portion of the friction transmission surface, and can form a fiber member that forms the friction transmission surface and joins with the vulcanization molding.

  The knitted fabric (or knitted fabric) may be either a weft knit (or a knitted fabric knitted by a weft knit) or a warp knit (or a knitted fabric knitted by a warp knit). A preferred knitted fabric is a weft knit (or a knitted fabric knitted by the weft knit).

  Further, the knitted fabric may be a single-layer knitted fabric knitted in a single layer or a multilayer knitted fabric knitted in multiple layers. In the weft knitting (or knitting structure of the weft knitting), examples of single-layer weft knitting include flat knitting (tadgetting knitting), rubber knitting, tack knitting, and pearl knitting. , Interlock, double rib, single picket, punch Rome, Milan rib, double jersey, Kanoko (Kanoko Omote, Kanoko Ura, Kanoko on both sides) and the like. In the warp knitting (or knitting structure of the warp knitting), single-layer warp knitting includes single denby and single cord, and multilayer warp knitting includes half tricot, double denby, double atlas and double cord. , Double tricot and the like. These knitted fabrics may be used alone or in combination of two or more to form a fiber member.

  Among the knitted fabrics having these knitting structures, a single-layer weft knitting (for example, a weft knitting with a flat knitting (tadashi knitting) as a knitting structure) or a multi-layer knitted fabric (for example, a knitting knitting (a knitting with a knitting knitting structure) Weft knitting) is preferred, and a multilayer knitted fabric is particularly preferred. When the fiber member is formed of a multi-layer knitted fabric, a bulky layer of the fiber member can be formed on the friction transmission surface, and the rubber composition forming the compression layer oozes on the surface side of the fiber member (the surface side of the friction transmission surface). Can be suppressed. Means for forming the bulky layer of the fiber member on the friction transmission surface include a method of increasing the number of layers of the knitted fabric, a method of increasing the bulk of the bulky processed yarn, and the like. In the multilayer knitted fabric, the number of layers of the knitted fabric may be, for example, 2 to 5, preferably 2 to 3, and more preferably 2 layers.

  In particular, when a knitted fabric (particularly, a multi-layer knitted fabric or a multi-layer knitted fabric structure) is formed by combining the bulky processed yarn at an appropriate ratio with respect to the cellulosic fiber, the frictional transmission surface (or the surface of the fiber member) is formed. Rubber exudation can be effectively prevented. Further, in the multilayer knitted fabric, in the layer on the friction transmission surface (or the surface of the fiber member) side in the thickness direction, more cellulose-based fibers are contained than in the layer on the side opposite to the friction transmission surface, so that the friction transmission The water absorption on the surface can be further improved. A multilayer knitted fabric containing a large number of cellulosic fibers in the layer on the friction transmission surface (or the surface of the fiber member) includes, for example, a layer on the friction transmission surface (or the surface of the fiber member) side of a plurality of layers. It may be produced by knitting only with the cellulosic fiber, or with the cellulosic fiber and the yarn containing the synthetic fiber, and knitting the opposite layer with the yarn containing the synthetic fiber (such as a polyester composite yarn). In the multilayer knitted fabric, the content of the cellulosic fiber may be increased continuously or stepwise toward the layer on the friction transmission surface (or the surface of the fiber member).

  In the case of a two-layer knitted fabric formed of a surface layer (a layer in contact with the pulley) on the friction transmission surface side and an inner layer on the opposite side, the ratio of the cellulosic fibers in the surface layer may be 50% by mass or more, and is preferable. Is 70% by mass or more, and may be 100% by mass in applications in which pronunciation resistance is important. For applications where abrasion resistance is important, the surface layer may be a combination of cellulosic fibers and synthetic fibers. When the cellulosic fiber and the synthetic fiber are combined in the surface layer, the mass ratio of the former and the latter is 99/1 to 50/50, preferably 90/10 to 60/40, and more preferably 80/20 to 70. / 30. The inner layer preferably contains synthetic fibers, and the ratio of the synthetic fibers can be selected from the range described in the section of the above-mentioned fiber member, but the ratio of the entire fiber member may be 50% by mass or more. It is preferably at least 80% by mass, more preferably 100% by mass. The mass ratio between the surface layer and the inner layer is the former / the latter = 95/5 to 50/50, preferably 90/10 to 60/40, and more preferably about 85/15 to 70/30.

  The density of the fiber or yarn in the fiber member (such as a knitted fabric) is, for example, 30 yarns / inch or more (for example, 32 to 70 yarns / inch, preferably 34 to 60 yarns / inch, or more in the wale direction and the course direction). (35 to 55 lines / inch). Further, the total number may be 60 lines / inch or more (for example, 62 to 120 lines / inch, preferably 70 to 115 lines / inch, more preferably 80 to 110 lines / inch, particularly 90 to 105 lines / inch). . A fiber member (such as a knitted fabric) having a predetermined fiber or yarn density does not have too large openings (or stitches), and has an excellent balance between wear resistance and water absorption. If the total density of the fibrous members is too low, the abrasion resistance may decrease and the water absorption may decrease.

Furthermore, the bulkiness of a fiber member (for example, a knitted fabric in which a composite yarn such as a bulky processed yarn is knitted as a synthetic fiber) can be selected within a range that can suppress oozing of rubber, and is, for example, 2 cm ³ / g or more (for example, 2.2). To 4.5 cm ³ / g), preferably about 2.4 cm ³ / g or more (for example, 2.5 to ⁴ cm ³ / g). The upper limit of the bulk is not particularly limited, for example, ^{4 cm} 3 / g or less (e.g. 2.3~3.8cm ³ / g), or 3.5 cm ³ / g or less (e.g. 2.5～3.3Cm ³ / G). The bulkiness (cm ³ / g) can be calculated by dividing the thickness (cm) of the knitted fabric by the mass per unit area (g / cm ² ).

The basis weight of the fiber member may be, for example, about 50 to 500 g / m ² , preferably about 80 to 400 g / m ² , and more preferably about 100 to 350 g / m ² .

(Isocyanate compound)
Since the composite fiber layer contains the isocyanate compound in addition to the fiber member, the abrasion resistance of the composite fiber layer is increased, and the durability (particularly, sound resistance) when wet is maintained for a long time. Specifically, since the isocyanate compound has a highly reactive isocyanate group, the functional group (the group having an active hydrogen atom such as a hydroxyl group or a carboxyl group) in the cellulose fiber constituting the fiber member or the rubber component of the compression layer described later is used. ) To improve the mechanical properties of the fiber member itself and the adhesion to the compression layer, thereby improving the wear resistance of the composite fiber layer. In the present invention, since the fiber member constituting the composite fiber layer is combined with an isocyanate compound, the resorcinol-formalin-latex liquid (RFL liquid) or epoxy resin, which is widely used as a fabric treatment agent, is not used, and the composite fiber layer is not used. Adhesiveness and mechanical properties can be improved.

  The isocyanate compound may have an isocyanate group as described above, but from the viewpoint of improving the abrasion resistance of the composite fiber layer, a polyisocyanate having a plurality of isocyanate groups (particularly, diisocyanate) is preferable.

  Further, the isocyanate compound may be a general-purpose isocyanate compound (for example, a polyisocyanate which is an isocyanate compound not protected by a blocking agent and which is exemplified as a polyisocyanate constituting a heat-reactive isocyanate compound described later). From the viewpoint that the elasticity of the fiber member is not impaired at the time of forming the belt, and after the vulcanization of the belt, it is hardened and the abrasion resistance can be increased, and the productivity of the belt can be improved. Isocyanate compound). Specifically, when the isocyanate compound is a heat-reactive type, the isocyanate group is protected by a blocking agent and is inactive when the belt is formed, and is not cured. Due to the heat generated, the blocking agent is dissociated, the isocyanate group is activated and reacts with the above-mentioned functional group to be cured. Therefore, when the heat-reactive isocyanate compound is used, the wear resistance of the belt can be increased without lowering the productivity of the belt.

  As the heat-reactive isocyanate compound, a conventional heat-reactive polyisocyanate (blocked isocyanate) can be used. Specifically, examples of the polyisocyanate constituting the heat-reactive polyisocyanate include aliphatic polyisocyanates [propylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate (TMDI), lysine Aliphatic diisocyanate such as diisocyanate (LDI), aliphatic triisocyanate such as 1,6,11-undecane triisocyanate methyloctane, 1,3,6-hexamethylene triisocyanate], alicyclic polyisocyanate [cyclohexane 1, 4-diisocyanate, isophorone diisocyanate (IPDI), hydrogenated xylylene diisocyanate, hydrogenated bis (isocyanatophenyl) meth Alicyclic diisocyanate such as diene, alicyclic triisocyanate such as bicycloheptane triisocyanate], aromatic polyisocyanate [phenylene diisocyanate, tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), tetramethyl xylylene diisocyanate] (TMXDI), naphthalene diisocyanate (NDI), bis (isocyanatophenyl) methane (MDI), toluidine diisocyanate (TODI), aromatic diisocyanate such as 1,3-bis (isocyanatophenyl) propane, and the like.

  These polyisocyanates include derivatives such as multimers (dimers, trimers, tetramers, etc.), adducts, modified (biuret-modified, allohanate-modified, urea-modified, etc.) and plural isocyanates It may be a urethane oligomer having a group.

  Examples of the modified or derivative of the polyisocyanate include an adduct of a polyisocyanate (such as an aliphatic polyisocyanate such as hexamethylene diisocyanate) and a polyhydric alcohol (such as trimethylolpropane or pentaerythritol), and a biuret of the polyisocyanate. And the multimers of the above-mentioned polyisocyanates can be preferably used. From the viewpoint of the adhesiveness and abrasion resistance of the composite fiber layer, a polymer of a polyisocyanate (for example, an aliphatic polyisocyanate) (for example, a polyisocyanate having an isocyanurate ring such as a trimer of hexamethylene diisocyanate) is used. Particularly preferred.

  Among these polyisocyanates, aliphatic polyisocyanates or derivatives thereof (for example, HDI or trimers thereof), aromatic polyisocyanates (TDI, MDI, etc.) are widely used.

Examples of the blocking agent (protective agent) for the heat-reactive isocyanate compound include _C1-24 monoalcohols such as methanol, ethanol, and isopropanol and alkylene oxide adducts thereof (for example, _C2-4 alkylene oxide such as ethylene oxide). Phenols such as phenol, cresol and resorcin; oximes such as acetoxime, methyl ethyl ketoxime and cyclohexane oxime; lactams such as ε-caprolactam and valerolactam; and secondary amines such as dibutylamine and ethyleneimine. And the like. These blocking agents can be used alone or in combination of two or more. Of these, oximes and lactams are widely used.

  The content of the isocyanate group in the heat-reactive isocyanate compound is not particularly limited, but may be, for example, about 1 to 50% by mass, preferably about 3 to 40% by mass, and more preferably about 5 to 30% by mass.

  The dissociation temperature of the heat-reactive isocyanate compound (the temperature at which the blocking agent dissociates and the active isocyanate groups are regenerated) is equal to or higher than the heating temperature in the belt forming step before the vulcanizing step of the rubber component (usually, the conjugate fiber described later). In the layer forming step, the drying temperature is not lower than the drying temperature of the fiber member impregnated with the liquid composition by immersion, and may be lower than the vulcanization temperature of the rubber component. Can be improved. The specific dissociation temperature may be, for example, 120 ° C. or higher (preferably 150 ° C. or higher, more preferably 180 ° C. or higher), for example, 120 to 250 ° C. (eg, 150 to 240 ° C.), preferably 160 to 230 ° C. (For example, 170 to 220 ° C.), and more preferably about 175 to 210 ° C. (particularly, 180 to 200 ° C.). If the dissociation temperature is too low, the drying temperature cannot be raised, so that it takes a long time to dry and the productivity may be reduced.

  The ratio of the isocyanate compound may be about 1 to 20% by mass in the composite fiber layer, and the flexibility and abrasion resistance of the belt can be compatible with each other. From 2 to 15% by mass, preferably from 3 to 13% by mass, more preferably from 4 to 12% by mass (e.g. In particular, about 4.5 to 10% by mass). If the proportion of the isocyanate compound is too small, the effect of improving the abrasion resistance may be reduced and the durability (particularly, sound resistance) at the time of being wet may be reduced. The flexibility may be reduced.

  The presence form of the isocyanate compound may be any form that covers at least a part of the fibers constituting the fiber member. As the distribution region of the isocyanate compound present in the fiber member, it may be present on the surface of the fiber member or between any of the fibers inside the fiber member. It is preferable that they are distributed substantially uniformly (particularly uniformly) over the entire fiber member including the space (porous structure). In the present invention, as described below, the isocyanate compound can be easily and uniformly distributed in the fiber member by a method of dipping the fiber member in the liquid composition containing the isocyanate compound and the resin component.

(Resin component)
The composite fiber layer contains a resin component in addition to the fiber member and the isocyanate compound, so that the composite fiber layer is released from the pin of the composite fiber layer sheet even if it is subjected to a tenter treatment in the composite fiber layer manufacturing process. Performance can be improved.

  As the resin component, any of a thermoplastic resin and a thermosetting resin may be used, various thermoplastic resins and thermosetting resins can be used, and the adhesion or tackiness to the pin by the isocyanate compound can be reduced, A non-adhesive resin or a non-adhesive resin may be used from the viewpoint that the releasability of the fiber member from the pin can be improved. Therefore, the viscosity of the resin component (B-type viscometer) in a 20% by mass aqueous solution (25 ° C.) is, for example, 1 to 100 mPa · s, preferably 3 to 50 mPa · s, more preferably 5 to 20 mPa · s (particularly 8 １５15 mPa · s). If the viscosity is too high, the permeability decreases, and it may be difficult to uniformly impregnate the inside of the fiber member. If the viscosity is too low, the amount of adhesion to the fiber member decreases, and the fiber member It may be difficult to attach a sufficient amount to the surface. In addition, from the viewpoint that the dispersibility of the liquid composition containing the isocyanate compound and the resin component can be improved, the liquid composition of the resin component (particularly, aqueous solution) is preferably anionic or neutral.

  Further, the number average molecular weight (GPC in terms of polystyrene) of the resin component may be, for example, 1,000 or more, preferably 2,000 to 30,000, and more preferably about 3,000 to 25,000. If the molecular weight is too small, the function of improving the releasability from the pin may be reduced. Conversely, if the molecular weight is too large, the abrasion resistance may be reduced, and the sound resistance of the belt may be reduced.

  The resin component may be a hydrophobic resin, but is preferably a hydrophilic resin because it can be dissolved or dispersed in an aqueous solvent and has a small environmental load. The hydrophilic resin may be a thermoplastic resin or a thermosetting resin having a hydrophilic group in a side chain and / or a main chain. Specific examples of the hydrophilic resin include a hydrophilic (meth) acrylic resin, a hydrophilic styrene resin, a vinyl acetate resin, a vinyl alcohol resin, a hydrophilic vinyl ether resin, a polyoxyalkylene glycol, and a hydrophilic polyester. Resins, hydrophilic polyamide resins, hydrophilic urethane resins, hydrophilic epoxy resins, cellulose derivatives and the like. These hydrophilic resins may be water-soluble resins or water-dispersible resins. These hydrophilic resins can be used alone or in combination of two or more. Among these, a point that can be appropriately reacted and / or bound to the isocyanate compound to improve the release property of the composite fiber layer sheet from the pins while maintaining the adhesiveness and mechanical properties of the composite fiber layer. Therefore, a hydrophilic polyester resin and a hydrophilic urethane resin are preferable.

  The hydrophilic polyester resin is, for example, a polyester resin obtained by reacting a dicarboxylic acid component or a reactive derivative thereof (lower alkyl ester, acid anhydride) with a diol component, or a polyester resin obtained by ring-opening polymerization of lactone. May be a resin in which a hydrophilic group is introduced.

Examples of the dicarboxylic acid component include aliphatic dicarboxylic acids (for example, C _4-14 aliphatic dicarboxylic acids such as adipic acid, suberic acid, azelaic acid, sebacic acid, and dodecane dicarboxylic acid), and alicyclic dicarboxylic acids ( Examples thereof include cyclohexanedicarboxylic acid and the like, and aromatic dicarboxylic acids (eg, phthalic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, and the like). These dicarboxylic acid components can be used alone or in combination of two or more. If necessary, the dicarboxylic acid component may be used in combination with a trivalent or higher polyvalent carboxylic acid such as trimellitic acid or pyromellitic acid.

Examples of the diol component include aliphatic diols (for example, C _2-10 such as ethylene glycol, trimethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, hexamethylene glycol, neopentyl glycol, and the like). Alkane diol, polyoxy _C2-4 alkylene glycol such as diethylene glycol and triethylene glycol, etc.), alicyclic diol, aromatic diol and the like. These diol components can be used alone or in combination of two or more.

  Examples of the lactone include butyrolactone, valerolactone, caprolactone, laurolactone and the like. These lactones can be used alone or in combination of two or more.

  Among these polyester resins, an aromatic dicarboxylic acid (such as terephthalic acid or naphthalenedicarboxylic acid) was used as a dicarboxylic acid component, and an alkanediol (such as ethylene glycol or 1,4-butanediol) was used as a diol component. Aromatic polyester resins are preferred.

  Examples of the method for introducing a hydrophilic group include a method using a diol component having a free carboxyl group or a tertiary amino group, and a method using a dicarboxylic acid component having a sulfonic acid group or a carboxylic acid group as a dicarboxylic acid component. Is mentioned. Among these, a method using an alkali metal salt such as sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfoisophthalic acid, and 4-sulfonaphthalene-2,7-dicarboxylic acid (for example, sodium 5-sulfoisophthalate). Is commonly used.

  The hydrophilic urethane-based resin may be, for example, a resin obtained by introducing a hydrophilic group into a urethane-based polymer obtained by reacting a diisocyanate component with a diol component.

  Examples of the diisocyanate component include the diisocyanate compounds exemplified as the polyisocyanate in the thermal reaction type isocyanate compound. The diisocyanate compounds can be used alone or in combination of two or more.

  Examples of the diol component include polyester diol, polyether diol, and the like in addition to the diol component exemplified as the diol component in the hydrophilic polyester-based resin. These diol components can be used alone or in combination of two or more.

  The polyester diol may be a reaction product of the diol component exemplified in the hydrophilic polyester-based resin and the dicarboxylic acid component exemplified in the hydrophilic polyester-based resin, and may be exemplified as the hydrophilic polyester-based resin. A ring-opened polymer of the lactone may be used.

The polyether polyol may be a poly _C2-6 alkylene glycol such as polyethylene glycol, polypropylene glycol, polybutylene glycol, and polytetramethylene ether glycol.

  As a method for introducing a hydrophilic group, for example, a method using polyethylene glycol having high hydrophilicity as a diol component, a method using a diol component having a free carboxyl group or a tertiary amino group (particularly, a high molecular weight diol), and the like are used. No. The diol used in the latter method is, for example, the diol component, a polycarboxylic acid having three or more carboxyl groups in the molecule or an anhydride thereof (for example, a 4-basic acid anhydride such as pyromellitic anhydride). Alternatively, it may be prepared by a reaction with a polycarboxylic acid having a sulfonic acid group (such as sulfoisophthalic acid), or a method using dimethylolpropionic acid or N-methyldiethanolamine. Tertiary amino groups may form quaternary ammonium salts.

  The hydrophilic urethane-based resin may be a heat-reactive urethane-based resin in which isocyanate groups are blocked. Examples of the blocking agent include the blocking agents exemplified as the blocking agent for the heat-reactive isocyanate compound. The dissociation temperature of the heat-reactive urethane-based resin may be the same as the dissociation temperature of the heat-reactive isocyanate compound, including the preferred range.

  The ratio of the resin component may be about 1 to 20% by mass in the composite fiber layer. From the viewpoint that the releasability of the composite fiber layer sheet from the pins can be improved while maintaining the wear resistance of the belt, For example, it is about 2 to 15% by mass, preferably about 2.1 to 10% by mass, and more preferably about 2.2 to 8% by mass (particularly 2.3 to 7.5% by mass). In applications where wear resistance is important, the proportion of the resin component may be about 1 to 7.5% by mass in the composite fiber layer, for example, 1.5 to 5% by mass, preferably 2 to 3% by mass, More preferably, it is about 2.1 to 2.5% by mass (particularly 2.2 to 2.4% by mass). If the proportion of the resin component is too small, the effect of improving the releasability of the composite fiber layer sheet from the pins may be reduced. Conversely, if the proportion is too large, the flexibility of the fiber member or the belt may be reduced.

The mass ratio of the resin component and the isocyanate compound, the former: the latter = 95: 5-20: 80 (e.g. 80: 20 to 20: 80) may be selected from the range of about, in terms of wear resistance, for example 90 : 10-30: 70, preferably 80 : 20-30: 70 , more preferably 85: 15-40: 60 (e.g. 80: 20-40: 60), most preferably 85: 15-50: 50. (For example, 85:15 to 70:30). If the amount of the resin component is too small, the releasability of the composite fiber layer sheet from the pins may be reduced. If the amount of the isocyanate compound is too small, the abrasion resistance is reduced and the durability when wetted (particularly, There is a possibility that the pronunciation resistance cannot be maintained for a long time.

  The resin component may be in any form as long as it covers at least a part of the fibers constituting the fiber member. As a distribution region of the resin component present in the fiber member, the resin component may be present on the surface of the fiber member or between the fibers inside the fiber member, but the releasability from the pins of the composite fiber layer sheet can be improved. Therefore, it is preferable that the resin be distributed substantially uniformly (particularly, uniformly) over the entire fiber member including the inner fibers (porous structure). In the present invention, as will be described later, the resin component can be easily and uniformly distributed in the fiber member by a method of immersing the fiber member in the liquid composition containing the isocyanate compound and the resin component.

(Characteristics of composite fiber layer)
The composite fiber layer may further include a curing agent for the isocyanate compound (for example, a polyol or a polyamine) in addition to the fiber member, the isocyanate compound, and the resin component. The ratio of the curing agent may be 100 parts by mass or less, for example, 0.1 to 50 parts by mass, preferably 0.5 to 30 parts by mass, more preferably 1 to 10 parts by mass with respect to 100 parts by mass of the isocyanate compound. Parts.

  The composite fiber layer may further include other components. Other components include conventional additives such as surfactants, dispersants, fillers, colorants, stabilizers, surface treatment agents, leveling agents, and the like. The proportion of the other component may be 10 parts by mass or less, for example, 0.01 to 5 parts by mass, preferably 0.1 to 3 parts by mass, more preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the cellulosic fiber. It is about 5 to 2 parts by mass.

  However, among the conventional additives, the composite fiber layer has a high abrasion resistance due to the isocyanate compound as described above, so that the conventional bonding treatment to the fiber is unnecessary, and the adhesive component other than the isocyanate compound is used. (Especially, resosirn-formaldehyde resin and epoxy resin). In the present specification and claims, the case where a small amount of an adhesive component that does not exhibit the effect as the adhesive component is included is synonymous with not including the adhesive component.

  The average thickness of the composite fiber layer may be 0.1 mm or more (for example, about 0.1 to 5 mm), for example, 0.2 to 3 mm, preferably 0.3 to 2 mm (for example, 0.5 to 1.5 mm). And more preferably about 0.7 to 1 mm (particularly 0.8 to 0.9 mm). If the thickness of the composite fiber layer is too small, the durability (particularly, soundproofing) when wet may decrease.

[Compressed layer]
The compression layer can usually be formed of rubber (or a rubber composition). Examples of the rubber (rubber constituting the rubber composition) include known rubber components and / or elastomers, for example, diene rubbers (natural rubber, isoprene rubber, butadiene rubber, chloroprene rubber, styrene butadiene rubber (SBR), acrylonitrile butadiene rubber) (Nitrile rubber), hydrogenated nitrile rubber (including a mixed polymer of hydrogenated nitrile rubber and an unsaturated carboxylic acid metal salt), etc., ethylene-α-olefin elastomer, chlorosulfonated polyethylene rubber, alkylated chlorosulfonated polyethylene Examples include rubber, epichlorohydrin rubber, acrylic rubber, silicone rubber, urethane rubber, and fluoro rubber. These components can be used alone or in combination. Among these rubber components, ethylene-α-olefin elastomers (ethylene-propylene rubber (EPM)) do not contain halogen having a large environmental load, have ozone resistance, heat resistance, and cold resistance, and are economically excellent. ), And ethylene-α-olefin-based rubbers such as ethylene-propylene-diene rubber (eg, EPDM).

  The ratio of the rubber to the entire compression layer (or the total amount of the rubber composition) is, for example, 20% by mass or more (eg, 25 to 80% by mass), preferably 30% by mass or more (eg, 35 to 75% by mass), and more preferably 40% by mass. % (For example, 45 to 70% by mass).

  The compression layer (or the rubber or rubber composition forming the compression rubber layer) may contain various additives as necessary. Examples of the additives (compounding agents) include known additives such as vulcanizing agents or cross-linking agents [eg, oximes (eg, quinone dioxime), guanidines (eg, diphenylguanidine), organic peroxides (eg, diacyl peroxide). , Peroxyesters, dialkyl peroxides, etc.), vulcanization aids, vulcanization accelerators, vulcanization retarders, reinforcing agents (such as silicon oxide such as carbon black and hydrous silica), and metal oxides (eg, oxidized Zinc, magnesium oxide, calcium oxide, barium oxide, iron oxide, copper oxide, titanium oxide, aluminum oxide, etc.), filler (clay, calcium carbonate, talc, mica, etc.), plasticizer, softener (paraffin oil, naphthenic) Oils such as oils), processing agents or processing aids (stearic acid, stearic metal salts, waxes, Anti-aging agents (aromatic amine-based anti-aging agents, benzimidazole-based anti-aging agents, etc.), adhesion improvers (melamine resins such as resorcinol-formaldehyde cocondensate, hexamethoxymethyl melamine, and co-condensation thereof) (Resorcin-melamine-formaldehyde cocondensate, etc.), coloring agents, tackifiers, coupling agents (silane coupling agents, etc.), stabilizers (antioxidants, ultraviolet absorbers, heat stabilizers, etc.), Examples thereof include a lubricant, a flame retardant, and an antistatic agent. These additives can be used alone or in combination, and these additives can be selected according to the type, use, and performance of the rubber.

  The proportion of the additive can also be appropriately selected according to the type of rubber and the like. For example, the ratio of the reinforcing agent (such as carbon black) is 10 parts by mass or more (for example, 20 to 150 parts by mass), preferably 20 parts by mass or more (for example, 25 to 120 parts by mass), based on 100 parts by mass of rubber. Preferably it is 30 parts by mass or more (for example, 35 to 100 parts by mass), particularly 40 parts by mass or more (for example, 50 to 80 parts by mass).

  The compression layer (or rubber composition) may include short fibers. As the short fibers, short fibers of the fibers exemplified as the fibers constituting the fiber member [for example, cellulosic short fibers such as cotton and rayon, polyester short fibers (such as PET short fibers), and polyamide short fibers (polyamide 6) Aliphatic polyamide short fibers, aramid short fibers, etc.). The short fibers may be used alone or in combination of two or more.

  The average fiber length of the short fibers may be, for example, about 0.1 to 30 mm (for example, 0.2 to 20 mm), preferably about 0.3 to 15 mm, and more preferably about 0.5 to 5 mm.

  These short fibers may be surface-treated with a surfactant, a silane coupling agent, an epoxy compound, an isocyanate compound, or the like, if necessary.

  The short fibers may be subjected to an adhesive treatment as needed in order to improve the adhesiveness with the rubber component. As the bonding treatment, a conventional bonding treatment can be used, for example, immersion in a resin-based treatment liquid in which an adhesive component [eg, an epoxy compound, an isocyanate compound] is dissolved in an organic solvent (toluene, xylene, methyl ethyl ketone, etc.). Treatment, immersion treatment in a resorcinol-formalin-latex liquid (RFL liquid), and immersion treatment in a rubber paste obtained by dissolving a rubber composition in an organic solvent.

  The proportion of the short fibers is, for example, 0.5 to 50 parts by mass (for example, 1 to 40 parts by mass), preferably about 3 to 30 parts by mass (for example, 5 to 25 parts by mass) with respect to 100 parts by mass of the rubber. Is also good.

  The average thickness of the compression layer (compression rubber layer or the like) can be appropriately selected according to the type of belt and the like, and may be, for example, about 1 to 30 mm, preferably about 1.5 to 25 mm, and more preferably about 2 to 20 mm.

[Core]
The core body is not particularly limited, but usually, core wires (twisted cords) arranged at predetermined intervals in the belt width direction can be used. The core wire is not particularly limited, and may include, for example, synthetic fibers such as polyester fibers (polyalkylene arylate fibers) and polyamide fibers (such as aramid fibers), and inorganic fibers such as carbon fibers.

  As the core wire, usually, a twisted cord using a multifilament yarn (for example, ply twist, single twist, Lang twist, etc.) can be used. The average core diameter (fiber diameter of the twisted cord) may be, for example, about 0.5 to 3 mm, preferably about 0.6 to 2 mm, and more preferably about 0.7 to 1.5 mm. The core wires may be embedded in the longitudinal direction of the belt, or may be embedded in parallel at a predetermined pitch in parallel with the longitudinal direction of the belt.

  In order to improve the adhesiveness with rubber, the core wire may be subjected to various types of adhesive treatment with an epoxy compound, an isocyanate compound, or the like, similarly to the short fibers.

[Stretch layer]
The extension layer may be formed of the same rubber composition as the compression layer, or may be formed of a cloth (reinforcement cloth) such as canvas. Examples of the cloth (reinforcement cloth) include cloth materials such as woven cloth, wide-angle canvas, knitted cloth, and nonwoven cloth. Of these, woven fabrics woven in the form of plain weave, twill weave, satin weave, and wide-angle canvas or knitted fabric having a warp and weft crossing angle of about 90 to 120 ° are preferable. As the fiber constituting the reinforcing cloth, the fibers exemplified in the section of the fiber member (such as water-absorbing fiber and non-water-absorbing fiber) can be used.

  The reinforcing cloth may be subjected to an adhesive treatment. As the bonding treatment, for example, the bonding treatment exemplified in the section of the short fiber may be performed. Further, instead of or after performing a conventional bonding treatment, a friction treatment in which the reinforcing cloth and the rubber composition are passed through a calender roll and the rubber composition is printed on the reinforcing cloth, rubber paste is applied to the reinforcing cloth. Spreading treatment for application and coating treatment for laminating a rubber composition on a reinforcing cloth may be performed.

  Further, the extension layer may be formed of rubber (rubber composition). The rubber composition may further contain the same short fibers as in the compression layer in order to suppress abnormal noise caused by the adhesion of the back rubber when the back is driven. The short fibers may be randomly oriented in the rubber composition. Further, the short fibers may be partially bent short fibers.

  Further, in order to suppress abnormal noise during driving on the back surface, an uneven pattern may be provided on the surface of the extension layer (the back surface of the belt). Examples of the concavo-convex pattern include a knitted cloth pattern, a woven cloth pattern, a drip woven cloth pattern, and an embossed pattern. Among these patterns, a woven fabric pattern and an emboss pattern are preferable. Further, at least a part of the back surface of the extension layer may be covered with the fiber resin mixed layer.

  The average thickness of the stretched layer can be appropriately selected according to the type of the belt, and may be, for example, about 0.5 to 10 mm, preferably about 0.7 to 8 mm, and more preferably about 1 to 5 mm.

[Adhesive layer]
The adhesive layer is not always necessary as described above. The adhesive layer (adhesive rubber layer) can be composed of, for example, the same rubber composition (rubber composition containing a rubber component such as ethylene-α-olefin elastomer) as the compressed layer (compressed rubber layer). The rubber composition of the adhesive layer may further contain an adhesion improver (resorcin-formaldehyde cocondensate, amino resin, etc.).

  The average thickness of the adhesive layer can be appropriately selected according to the type of the belt, and may be, for example, about 0.2 to 5 mm, preferably about 0.3 to 3 mm, and more preferably about 0.5 to 2 mm.

  In the rubber composition of the extension layer and the adhesive layer, a rubber of the same type or the same type as the rubber component of the rubber composition of the compression rubber layer is often used as the rubber component. In these rubber compositions, vulcanizing agents or crosslinking agents, co-crosslinking agents or crosslinking aids, the proportion of additives such as vulcanization accelerators, respectively, from the same range as the rubber composition of the compression layer You can choose.

[Production method of friction transmission belt]
The method for producing a friction transmission belt according to the present invention includes the steps of: dipping a fiber member in a liquid composition containing an isocyanate compound and a resin component; and heat setting the fiber member impregnated with the liquid composition with a pin tenter to form a composite fiber layer. Forming the composite sheet.

(Composite fiber layer forming step)
In the composite fiber layer forming step, the immersion treatment of the fiber member in the liquid composition and the heat-setting treatment of the fiber member impregnated with the liquid composition by immersion are usually continuously performed, and both treatments are performed. Is referred to as tenter treatment.

  FIG. 2 shows an example of the tenter treatment. The fiber member 11 fed from the roll body is first immersed in a dip bath 13 filled with a liquid composition 12 containing an isocyanate compound and a resin component. A dip process is performed to remove excess liquid composition. Then, while holding the left and right ends of the fiber member impregnated with the liquid composition with the plurality of pins of the pin tenter 15, the fibrous member is passed through a hot-air drying furnace 16 and subjected to a heat setting process of drying and tentering. . Thereafter, the fiber member (the composite fiber layer sheet obtained by drying) is removed from the pins of the tenter and wound up.

  In the composite fiber layer forming step, the immersion treatment (dipping treatment) is excellent in workability, and easily penetrates the liquid composition into the interior of the fiber member, and the isocyanate compound and the resin component are present on the surface and inside of the fiber member. Can be distributed substantially uniformly, and the fiber surface can be coated almost uniformly over the entire fiber member with the isocyanate compound and the resin component.

  The liquid composition containing the isocyanate compound and the resin component may contain a solvent. As the solvent, a hydrophobic organic solvent may be used, but an aqueous solvent (water, a lower alcohol such as ethanol or isopropanol, a ketone such as acetone, etc.) is preferable, and water is particularly preferable, because the environmental load is small.

  The ratio of the isocyanate compound in the liquid composition (solid content concentration) is determined by increasing the abrasion resistance while maintaining the workability and the flexibility of the fiber member and belt, and improving the durability when wet (especially, sound resistance). From the viewpoint that the above properties can be maintained over a long period of time, it is, for example, about 0.5 to 10% by mass, preferably 1 to 8% by mass, and more preferably about 1.5 to 5% by mass (particularly 2 to 4% by mass). . If the proportion of the isocyanate compound is too small, the effect of improving the abrasion resistance may decrease. Conversely, if the proportion is too large, the workability may decrease due to an increase in the viscosity of the aqueous solution, and the flexibility of the fiber member or belt may also decrease. There is.

  The ratio of the resin component (solid content) in the liquid composition is such that the workability and the flexibility of the fibrous member and the belt can be kept good and the releasability of the composite fiber layer sheet from the pin can be improved. For example, it is about 0.5 to 10% by mass, preferably about 1 to 8% by mass, and more preferably about 1 to 5% by mass (particularly 1 to 3% by mass). If the proportion of the resin component is too small, the effect of improving the releasability may decrease. Conversely, if the proportion is too large, the workability may decrease due to an increase in the viscosity of the aqueous solution, and the flexibility of the fiber member and the belt may also decrease. There is.

Mass ratio of the isocyanate compound and the resin component of the liquid composition, the former: the latter = 95: 5-20: can be selected from about 80 range, in terms of wear resistance, for example 90: 10-30: 70, It is preferably about 85:15 to 40:60, more preferably about 85:15 to 50:50, and most preferably about 85:15 to 70:30. If the amount of the resin component is too small, the releasability of the composite fiber layer sheet from the pins may be reduced. If the amount of the isocyanate compound is too small, the abrasion resistance is reduced and the durability when wetted (particularly, There is a possibility that the pronunciation resistance cannot be maintained for a long time.

  In the present invention, since the isocyanate compound and the resin component are combined, handling of the liquid composition is excellent. That is, when an RFL solution, which is a conventional treating agent, is used, a long time aging is required for preparing the solution and the productivity is reduced. However, a liquid composition containing an isocyanate compound and a resin component (particularly, an isocyanate compound and a hydrophilic compound) is used. (Aqueous solution containing resin) can be used only by diluting, and the productivity can be improved. Furthermore, among isocyanate compounds, if it is a general-purpose isocyanate compound, curing gradually progresses even in the state of the immersion liquid and the handleability decreases, but when a heat-reactive isocyanate compound is used, the life as the immersion liquid is extended. It is easy to handle and can improve productivity.

  In the heat setting treatment, the fiber member impregnated with the liquid composition is widened by a pin tenter and heated and dried by being transported in a drying furnace. By drying the liquid composition permeated into the fiber member, the isocyanate compound can be attached to the surface of the fiber from the inside to the surface of the fiber member. The drying temperature, when a heat-reactive isocyanate compound is used as the isocyanate compound, can suppress the activation and curing of the isocyanate compound due to heating in the drying treatment to reduce the flexibility of the fiber member, and the elongation of the fiber member can be reduced. From the point that the shape defect of the belt due to shortage can be suppressed, it is sufficient to dry at a temperature lower than the dissociation temperature of the heat-reactive isocyanate compound, and when the dissociation temperature is T, it may be T-10 ° C or lower, For example, T-120 ° C to T-20 ° C, preferably T-100 ° C to T-30 ° C, more preferably T-90 ° C to T-50 ° C. The specific drying temperature may be lower than 120 ° C, for example, about 60 to 115 ° C, preferably about 80 to 110 ° C, and more preferably about 90 to 105 ° C.

  The drying time is not particularly limited, but in the present invention, by using a heat-reaction type isocyanate compound having a high dissociation temperature as the isocyanate compound, drying can be performed at a relatively high temperature, so that the drying time can be shortened and the productivity of the belt can be improved. . The drying time may be 30 minutes or less (especially 10 minutes or less), for example, about 0.5 to 10 minutes, preferably about 1 to 8 minutes, and more preferably about 3 to 7 minutes.

  As the pin tenter, a general-purpose pin tenter in which the pin portion and the pin sheet are formed of a metal such as iron or stainless steel can be used. In the present invention, since the isocyanate compound and the resin component are combined, the release treatment on the pin portion surface is performed. Heat set processing can be performed smoothly without special processing such as. The height of the pin portion is, for example, about 5 to 30 mm (particularly, 10 to 20 mm). The transport speed of the fiber member by the pin tenter is, for example, about 1 to 25 m / min (particularly, about 5 to 15 m / min).

(Coating process)
Except for the composite fiber layer forming step, the friction transmission belt of the present invention can use a conventional friction transmission belt manufacturing method, and can be manufactured through a coating step of coating a compression layer with a composite fiber layer. In the coating step, for example, a composite fiber layer sheet, a compression layer made of rubber (or a rubber composition), a core, and an extension layer are laminated, and the obtained laminate is molded into a cylinder using a molding die. By forming into a shape, vulcanizing to form a sleeve, and cutting the vulcanized sleeve to a predetermined width, a belt in which the composite fiber layer covers the compression layer can be produced.

  More specifically, the V-ribbed belt can be manufactured, for example, by the following method.

(First manufacturing method)
First, an unvulcanized sheet for an extension layer is wound around a flexible jacket on the outer peripheral surface using a cylindrical inner mold having a flexible jacket attached on the outer peripheral surface, and a core wire for forming a core on the sheet is used. The (twisted cord) is helically spun, and an unvulcanized sheet for the compression layer and a sheet for the composite fiber layer are wound to form a laminate. Next, as the outer mold that can be mounted on the inner mold, a cylindrical outer mold having a plurality of rib molds engraved on an inner peripheral surface is used, and the inner mold around which the laminate is wound is used in the outer mold. , Installed concentrically. Thereafter, the flexible jacket is expanded toward the inner peripheral surface (rib type) of the outer die, and the laminate (compressed layer) is pressed into the rib type and vulcanized. Then, a sleeve-shaped V-ribbed belt can be manufactured by removing the inner mold from the outer mold and removing the vulcanized rubber sleeve having a plurality of ribs from the outer mold. The sleeve-shaped V-ribbed belt may be manufactured by cutting the vulcanized rubber sleeve to a predetermined width in the belt longitudinal direction using a cutter, if necessary. According to the first manufacturing method, a laminate including an extension layer, a core, a compression layer, and a composite fiber layer can be expanded at a time to finish a sleeve having a plurality of ribs (or a V-ribbed belt).

(Second manufacturing method)
In connection with the first production method, for example, a method disclosed in Japanese Patent Application Laid-Open No. 2004-82702 (only a composite fiber layer and a compression layer are expanded to form a preform (semi-vulcanized state), and then an extension layer And a core body that is expanded and pressure-bonded to the preformed body, vulcanized and integrated, and finished into a V-ribbed belt).

  Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. Hereinafter, a method for preparing a rubber composition, a method for producing a belt, a method for measuring or evaluating each physical property, and the like will be described.

[Rubber composition]
The rubber composition shown in Table 1 was kneaded with a Banbury mixer, and the kneaded rubber was passed through a calender roll to produce an unvulcanized rolled rubber sheet (compression layer sheet) having a predetermined thickness. Further, using the rubber composition shown in Table 1, a sheet for an extension layer was produced in the same manner as the sheet for a compression layer. The components in Table 1 are as follows.

EPDM: “Nodel IP4640” manufactured by Dow Chemical Company
Zinc oxide: manufactured by Shodo Chemical Co., Ltd., "3 types of zinc oxide"
Carbon black: manufactured by Tokai Carbon Co., Ltd., "Seast V", average particle size 55 nm
Softener: paraffin oil, Idemitsu Kosan Co., Ltd., "NS-90"
Anti-aging agent: "Nocrack MB" manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
Organic peroxide: manufactured by NOF Corporation, "Park Mill D-40"
Co-crosslinking agent: "Barnock PM" manufactured by Ouchi Shinko Chemical Co., Ltd.

[Knitted fabric immersion liquid]
The isocyanate solution and the resin component (or the isocyanate solution alone) shown in Table 2 were diluted with water to prepare an immersion liquid having the concentration shown in Table 2. The components in Table 2 are as follows.

Isocyanate solution: “Elastron BN-27” manufactured by Daiichi Kogyo Seiyaku Co., Ltd., dissociation temperature 180 ° C, solid content concentration 30% by mass
Polyester resin solution: Takamatsu Yushi Co., Ltd. “Hard Finishing Agent TK Set X-500”, polyester polymer copolymer resin, solid content concentration 20% by mass, anionic polyurethane resin solution: Nika Chemical Co., Ltd. “Casesol” UH-150 ", self-emulsifying polyurethane resin, solid content concentration 36%, anionic

Examples 1 to 7 and Reference Example 1
[Preparation of knitted fabric impregnated with heat-reactive isocyanate and resin component]
In Examples 1 to 6 and Reference Example 1, a cotton spun yarn (40 count, one yarn) as a cellulosic fiber and a PTT / PET conjugate composite yarn (fineness of 84 dtex) as a synthetic fiber were mixed with a cellulosic fiber / A knitted fabric (fiber member) having a knitting structure of weft knitting (kanoko, two layers) was produced by knitting at a mass ratio of synthetic fibers of 80/20. The thickness of the obtained knitted fabric was 0.85 mm, and the knitted fabric density (wale + course) was 100 yarns / inch. Further, the surface layer was formed of cellulosic fibers, and the inner layer was formed of synthetic fibers.

  In Example 7, a cotton spun yarn (40 count, one yarn) as a cellulosic fiber and a PTT / PET conjugate composite yarn (fineness of 84 dtex) as a synthetic fiber were mixed with a cellulosic fiber / synthetic fiber = 60/40. And the knitting structure was made into a knitted fabric (fiber member) having a weft knitting (kanoko, two layers). The thickness of the obtained knitted fabric was 0.85 mm, and the knitted fabric density (wale + course) was 100 yarns / inch. The surface layer contained cellulosic fibers and synthetic fibers at a mass ratio of the former / the latter = 75/25, and the inner layer was formed of synthetic fibers.

  The average thickness of the knitted fabric and the density of the knitted fabric were measured as follows. The average thickness of the knitted fabric is in accordance with JIS L 1096 (2010). Except for unnatural wrinkles and tension, place the knitted fabric on a flat table, and measure the thickness at five places using a constant load type thickness gauge. Then, an average value was calculated and defined as an average thickness. The density of the knitted fabric is in accordance with JIS L 1096 (2010), and the knitted fabric is placed on a flat table except for unnatural wrinkles and tension. It measured, calculated the average value, and set it as the average density.

  After immersing the obtained knitted fabric in immersion liquids A to G for 10 seconds, excess immersion liquid was dropped with a squeezing roll, and then a pin tenter component having a pin mounted on a pedestal [pin having a diameter of 1 mm and a length of 15 mm] 3 are alternately arranged in parallel in two rows (interval of 3 mm) at intervals of 10 mm, respectively, as shown in FIG. Dried for 10 minutes (tenter treatment). After drying, the knitted fabric is pulled up by hand to check for damage to the composite fiber layer sheet, and to evaluate the releasability of the composite fiber layer sheet from the pins according to the following criteria. The results are shown in Table 3.

：: The composite fiber layer sheet was smoothly removed from the pin and the composite fiber layer sheet was not damaged. ×: The composite fiber layer sheet was not smoothly removed from the pin and the composite fiber layer sheet was deformed or torn. .

[Preparation of V-ribbed belt]
An unvulcanized sheet for an extension layer is wound around the flexible jacket on the outer peripheral surface using a cylindrical inner mold having a flexible jacket on the outer peripheral surface, and a core wire (twisted cord) serving as a core is wound on the sheet. ) Is spirally spun, and an unvulcanized sheet for a compression layer and a sheet for a composite fiber layer (a knitted fabric impregnated with a heat-reactive isocyanate and a resin component, or a knitted fabric impregnated with a heat-reactive isocyanate) are laminated. Was prepared. Note that an aramid cord having a 1100 dtex / 1 × 4 configuration was used for the cord. In order to improve the adhesion to rubber, the core wire is immersed in a resorcinol-formalin-latex solution (RFL solution) in advance, and then coated with a treatment solution obtained by dissolving a rubber composition containing EPDM in an organic solvent (toluene). Processing was performed.

  The inner mold around which the tubular laminate is wound is placed concentrically in a tubular outer mold in which a plurality of rib molds are engraved on the inner peripheral surface, and the flexible jacket is expanded to form the laminate. It was pressed into a rib mold and vulcanized at 180 ° C. Then, the inner mold is extracted from the outer mold, the vulcanized rubber sleeve having a plurality of ribs is removed from the outer mold, and the vulcanized rubber sleeve is cut into a predetermined width in a belt longitudinal direction by using a cutter. (Number of ribs: 6, peripheral length: 980 mm, belt shape: K shape, belt thickness: 4.3 mm, rib height: 2 mm, rib pitch: 3.56 mm) were produced.

[Durability test conditions]
140 mm diameter driving pulley (Dr.), 60 mm diameter tension pulley 1 (Ten.1), 50 mm diameter driven pulley 1 (Dn.1), 60 mm diameter tension pulley 2 (Ten.2), 111 mm diameter driven A durability test was performed by running the belt using a tester shown in FIG. 4 in which pulleys 2 (Dn. 2) were sequentially arranged. The obtained V-ribbed belt is hung on each pulley of the testing machine, the rotation speed of the driving pulley is varied at 800 ± 160 rpm, the load on the driven pulley 1 is 16 N · m, the driven pulley 2 is unloaded, and the belt tension is changed. Was 200N / 6 rib. Water was injected from the compression layer side of the belt at the center of the driving pulley and the driven pulley 2. Water injection was performed once every 60 seconds (5 seconds), and the water injection amount was 100 cc / second (500 cc / 5 seconds). The test temperature was 25 ° C. and the test time was 60 minutes.

[Wear test conditions]
The belt was run by using a test machine shown in FIG. 5 in which a drive pulley (Dr.) having a diameter of 60 mm, a tension pulley (Ten.) Having a diameter of 125 mm, and a driven pulley (Dn.) Having a diameter of 60 mm were arranged in this order. The test was performed. The obtained V-ribbed belt was hung on each pulley of the testing machine, and a load was applied so that the belt tension became 170N. The slip ratio was adjusted to 4% by setting the rotation speed of the driving pulley to 2000 rpm and the rotation speed of the driven pulley to 1920 rpm. The test temperature was 25 ° C. and the test time was 72 hours. The mass of the belt before and after the test was measured, and the wear rate was calculated based on the following equation.
Abrasion rate (%) = [(Belt mass before abrasion test−Belt mass after abrasion test) / Belt mass before abrasion test] × 100

  The V-ribbed belts obtained in Examples 1 to 7 and Reference Example 1 were run under the durability test conditions, and the slip ratio before and after the durability test, the presence or absence of sound generation during the water injection after the durability test, and the friction after the durability test. Table 3 shows the results of confirmation of the appearance of the transmission surface and the results of the wear test.

  In addition, the adhesion rate in Table 3 can be calculated based on the following equation.

    Adhesion rate (%) = [(weight of sheet for composite fiber layer after tenter treatment-weight of fiber member before tenter treatment) / weight of sheet for composite fiber layer after tenter treatment] × 100

  As is clear from the results in Table 3, Reference Example 1 using the knitted fabric impregnated only with the isocyanate compound has low releasability from the pin, has a problem in workability, and cannot be mass-produced using a pin tenter. there were. On the other hand, in Examples 1 to 7 using the knitted fabric impregnated with the isocyanate compound and the resin component, the releasability from the pin was good. Further, there was no increase in the slip ratio even after the durability test, and it was determined that the transmission performance was sufficient for practical use. Furthermore, the abrasion resistance was also excellent.

  In Examples 1 and 2, no abnormal noise was generated, and no change was observed in appearance. On the other hand, in Example 3 in which the adhesion ratio of the isocyanate compound was low, abnormal noise was generated, and the result was a little inferior in that the soundproofing resistance when wet was maintained for a long period of time. No remarkable difference was observed in Examples 1 to 3 using a polyester resin as a resin component and Examples 4 to 6 using a polyurethane resin in terms of mold releasability, sound resistance and the like.

  In Example 7, no abnormal noise was generated, and no change was observed in appearance. In addition, since the surface layer contained synthetic fibers, the abrasion resistance was the highest, although the isocyanate adhesion rate was slightly lower than in Examples 1 and 4. Furthermore, surprisingly, even though the proportion of the cellulosic fiber in the surface layer was smaller than that of Examples 1 to 6, the pronunciation resistance was also excellent. It is presumed that the reason why the pronunciation resistance was also excellent was that the detachment of the cellulosic fiber was suppressed by the improvement of the wear resistance.

  The friction transmission belt of the present invention can be used as a friction transmission belt such as a flat belt, a V belt, and a V-ribbed belt. Further, since the friction transmission belt of the present invention can improve the quietness when it is wet, it can be suitably used for high-load transmission equipment used outdoors, such as automobiles, motorcycles, and agricultural machines.

1: friction transmission belt (V-ribbed belt)
2 ... compression layer 3 ... core body 4 ... extension layer 5 ... composite fiber layer

Claims (14)

  A friction transmission belt in which a friction transmission surface is formed of a fiber member, a composite fiber layer containing an isocyanate compound and a resin component, wherein the fiber member includes cellulosic fibers.   The friction transmission belt according to claim 1, wherein the ratio of the isocyanate compound and the resin component in the composite fiber layer is 2 to 15% by mass, respectively.   The friction transmission belt according to claim 1 or 2, wherein the mass ratio of the isocyanate compound and the resin component is 95: 5 to 20:80.   The friction transmission belt according to any one of claims 1 to 3, wherein the isocyanate compound is a heat-reactive isocyanate compound.   The friction transmission belt according to claim 4, wherein the thermal reaction type isocyanate compound has a dissociation temperature of 120C or more.   The friction transmission belt according to any one of claims 1 to 5, wherein the resin component is a hydrophilic resin.   The friction transmission belt according to any one of claims 1 to 6, wherein the cellulosic fiber is a spun yarn formed of cellulose.   The friction transmission belt according to any one of claims 1 to 7, wherein the fiber member further includes a synthetic fiber.   The friction transmission belt according to any one of claims 1 to 8, which is a V-ribbed belt.   After immersing the fiber member in the liquid composition containing the isocyanate compound and the resin component, the fiber member impregnated with the liquid composition is heat-set using a pin tenter to form a composite fiber layer sheet by forming a sheet for the composite fiber layer. The method for producing a friction transmission belt according to claim 1, comprising a step.   The production method according to claim 10, wherein the liquid composition is an aqueous solution containing a heat-reactive isocyanate compound and a hydrophilic resin.   The method according to claim 11, wherein the fiber member impregnated with the liquid composition by immersion is dried at a temperature lower than a dissociation temperature of the heat-reactive isocyanate compound.   The method according to any one of claims 10 to 12, wherein the ratio of the isocyanate compound and the resin component in the liquid composition is 1 to 8% by mass, respectively.   14. The production method according to claim 13, wherein the mass ratio of the isocyanate compound and the resin component in the liquid composition is 95: 5 to 20:80.

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